Packaging Machine and Packages Made Therewith

ABSTRACT

Provided herein is a liquid-filled, non-reclosable tetrahedral or pillow-shaped packaging container having a longitudinal fin seal and a pair of transverse seals. In the case of tetrahedral packages, the transverse seals are perpendicular to one another. Also provided herein is an apparatus for the formation of such fin seals as part of a continuous packaging and filling operation. A third aspect of the apparatus of the present disclosure is the development of a heated jaw that exhibits consistent heating across the jaw face. Yet another feature of the apparatus of the present disclosure is provided in a modified, closed-loop electrical system for real-time monitoring and adjustment of the temperatures of the heated jaws, as they are moving.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and is a divisional of, co-pendingU.S. patent application Ser. No. 11/985,456 entitled “Packaging Machineand Packages Made Therewith,” which was filed on Nov. 15, 2007, and ishereby entirely incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to improvements in continuous fillpackaging machines and, particularly, to machines that produceliquid-filled packages and to the packages produced thereby. Generally,the packages are non-reclosable, tetrahedral-shaped containers having acentral longitudinal seal and opposite transverse seals that areoriented perpendicularly to one another. Described herein are equipmentand processes for forming fin-shaped seals in the longitudinaldirection, which are useful in situations where an overlapping seal maybe inadequate or vulnerable. Also described herein are improvements tothe heated jaws that produce the transverse package seals and to thecorresponding power supply system for such heated jaws. Suchimprovements enable the continuous production of liquid-filledcontainers having strong seals in both the longitudinal and transversedirections.

BACKGROUND

Machines that are designed to produce cushion-shaped,parallelepedic-shaped, or tetrahedral-shaped packages from a continuousroll or flat web of packaging material are well known in the packagingindustry. Often, such packages are used to hold single servings ofconsumable food products. Representative items include liquids such asfruit juice and non-carbonated beverages (which may remain liquid or besubsequently flash-frozen into solids) and semi-solids, such as sourcream or other viscous sauces.

Commonly, such packaging machines are of the “form-fill-seal” variety,in which a continuous flat web of suitable packaging material (e.g.,wax- or plastic-coated paper) is formed into a vertically orientedtube-like structure by means of passing the web through one or morering-like guides or forming collars, with a longitudinal seal formed byadhesively or thermally joining the opposed longitudinal edges of theweb, often in overlapping configuration.

Once a tube of packaging material is produced, the product is introducedand it is necessary to form transverse seals to create a string ofconnected, filled packages. Opposed sets of heated and pressure jawscompress the tube, in spaced intervals, as the tube is moved through themachine. The string of connected packages may then be separated from oneanother by cutting the sealed tube segments in the region of thetransverse seals.

Because the transverse seals are bisected to produce individualpackages, it has been found that these transverse seals are most proneto leakage. While such leakage is less problematic when the product isfrozen or very viscous (such as is the case with sour cream), theleakage rate is typically unacceptable for liquid products (such asjuice or other beverages). Most often, the poor transverse seal isattributable to temperature variation from one heated jaw to another.The reason for this problem in machines of this type is that the heatedjaws are constantly moving along an oval or elliptical path, which makesmonitoring and adjustment of the jaw temperatures difficult.

The present disclosure addresses this deficiency in currently availableequipment by providing a closed-loop electrical system for powering theheated jaws that includes equipment for monitoring the temperature ofthe jaw faces and for adjusting the power supplied to those jaw faces inreal-time. As a result, the temperature differential among the heatedjaws is considerably smaller than that of previous heated jaws, whichare part of an open-loop control system.

Another issue related to existing packages with an overlapping seal isthat one of the cut longitudinal edges of the packaging material isexposed to the food product. When the food products are acidic innature, such as some juices or ketchup, or when the food products areaqueous and the packaging material includes a wickable layer (e.g.,paper), the food products tend to “attack” the exposed cut edge of thepackaging material. As a result, the longitudinal seals becomesusceptible to failure. By incorporating a “fin”-type seal in place ofthe traditional overlap seal, the cut edges of the packaging materialremain on the outside of the formed package, and a more reliablelongitudinal seal is formed. Provided herein is a subassembly forforming a fin seal on a continuous-fill packaging machine.

SUMMARY

Provided herein is a liquid-filled, non-reclosable tetrahedral orpillow-shaped packaging container having a longitudinal fin seal and apair of transverse seals. In the case of tetrahedral packages, thetransverse seals are substantially perpendicular to one another. Thesetypes of packages may be preferred for many applications, because thesurface area-to-volume ratio is better than for pillow-shaped packages(that is, less surface area of packaging material is needed per unit ofvolume). The packages may be formed of paper, film, or foil, whichinclude a meltable layer on one side. The packages are designed tocontain liquid and semi-solid food products, including beverages (suchas fruit juice, sweetened beverages, and coffee flavorings); condiments(such as ketchup, mustard, and salad dressing); and viscous semi-solids(such as sour cream or mayonnaise).

Also provided herein is an apparatus for the formation of such fin sealsas part of a continuous packaging and filling operation. The apparatusincludes a tube-forming subassembly, a seal-heating subassembly, aseal-pressing subassembly, and a tube-conveying subassembly. In thetube-forming subassembly, the stock material is fed such that themeltable layer on one side of the stock material is positioned towardthe inside of the device. Then, the longitudinal edges of the stockmaterial are positioned through a slot that holds the respectiveinterior sides against one another, such that the meltable layers are incontact with each other. The area adjacent to the longitudinal edges isthen heated by the seal-heating subassembly to melt the meltable layeron the stock material, and the longitudinal fin seal is formed bypressing the longitudinal edges together in the seal-pressingsubassembly. The tube-conveying subassembly pulls the formed tubethrough the apparatus and into the transverse sealing subassembly.

A third aspect of the apparatus of the present disclosure is provided ina closed-loop heated jaw system for real-time monitoring and adjustmentof the temperatures of the heated jaws, as they are moving. The heatedjaw system includes thermocouples that monitor the temperature of thejaw face; wireless transmitters that transmit the temperature readingsto an antenna; an antenna that powers the wireless transmitters,receives the data, and transmits the data to a programmable logiccontroller; a pair of power rails that provide power to the heated jawsand that include a base level portion and a power-correction portion;and a programmable logic controller that controls the power supplied tothe base level portion and the power-correction portion of the powerrails. Using this closed-loop system, the temperature variation amongthe heated jaws is minimized, thereby ensuring consistent formation ofstrong transverse seals.

The various subassemblies described above and herein provide acontinuous-fill packaging machine, particularly useful for liquid foodproducts. The resulting packages have reliable and durable seals in boththe longitudinal direction and the transverse direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front view of a tetrahedral package formed in accordancewith the teachings herein;

FIG. 1B is another view of the tetrahedral package formed in accordancewith the teachings herein;

FIG. 1C is a parallelepedic package having a fin seal, which may beformed in accordance with the teachings herein;

FIG. 2 is a schematic representation of a packaging machine of thepresent disclosure, which is equipped with a fin seal-forming assembly;

FIG. 3 is an isometric view of the fin seal-forming assembly of thepresent disclosure;

FIG. 4 is a cross-sectional view of a tube-forming subassembly of thefin seal-forming assembly, as taken along Line 4-4 of FIG. 3;

FIG. 5 is a plan view of the tube-forming ring of FIG. 4;

FIG. 6A is a plan view of a fin seal-heating subassembly, in which thefin seal heater arms are in an open position;

FIG. 6B is a plan view of the fin seal-heating subassembly of FIG. 6A,in which the fin seal heater arms are in a closed position;

FIG. 6C is a close-up plan view of the fin seal heater arms of FIG. 6B,as in contact with a strip-shaped sheet of packaging material;

FIG. 7 is a cross-sectional view of a fin seal-pressing subassembly, astaken along Line 7-7 of FIG. 3;

FIG. 8 is a close-up plan view of the fin seal-pressing subassembly ofFIG. 7;

FIG. 9A is a cross-sectional view of a tube-conveying subassembly, astaken along Line 9-9 of FIG. 3;

FIG. 9B is a three-dimensional, isometric view of the tube-conveyingsubassembly, showing the drive mechanism for the tube-conveyingsubassembly;

FIG. 10A is a schematic representation of a package-forming subassembly,in which the cooperative relationship between pressure jaws 38 andheated jaws 36 is illustrated and in which a closed-loop power supplysubassembly is represented;

FIGS. 10B-10J illustrate the various embodiments of the backs of heatedjaws having two or more electrical contacts for use in variousembodiments of the closed-loop electrical systems provided herein;

FIG. 10B is a schematic representation of the back 510 of a heated jaw,showing the electrical contacts 141′ and 142′;

FIG. 10C is an isometric view of a closed-loop, modified electricalsystem 140 having two power rails 141, 142, which shows the placement ofseven heated jaws and their respective electrical contacts, and whichfurther shows a power-correction portion 144 of power rail 142, thepower-correction portion having a length that is equal to, or slightlyless than, the distance (or “pitch”) between adjacent jaws;

FIGS. 10D and 10E are schematic representations of alternate versions612, 614 of the back of a heated jaw, showing electrical contacts 341′,342′, and 346′, for use with the electrical system of FIG. 10F;

FIG. 10F is an isometric view of a closed-loop, modified electricalsystem 340 having three power rails 341, 342, and 346, which shows thepositioning of eight heated jaws and their respective electricalcontacts, and which further shows a pair of power-correction portions344, 348, the power-correction portions having a length that is twice,or slightly less than twice, the pitch between adjacent jaws;

FIGS. 10G, 10H, and 10I are schematic representations of alternateversions 710, 712, 714 of the back of a heated jaw, for use with theelectrical system of FIG. 10J;

FIG. 10J is an isometric view of a closed-loop, modified electricalsystem 540 having four power rails 541, 542, 546, and 548, which showsthe positioning of nine heated jaws and their respective electricalcontacts, and which further shows three power-correction portions 543,547, and 549, the power-correction portions having a length that isthree times, or slightly less than three times, the pitch betweenadjacent jaws;

FIG. 11 is an isometric view illustrating the formation of a chain oftetrahedral packages, showing the cooperative relationship of heatedjaws and pressure jaws;

FIG. 12 is an isometric view of a first heated jaw subassembly of thepresent disclosure;

FIG. 13 is an isometric view of a second heated jaw subassembly of thepresent disclosure;

FIG. 14 is an isometric view of a pressure jaw subassembly, whichfunctions in cooperation with the heated jaw subassembly of FIG. 12 orFIG. 13;

FIG. 15A is a cross-sectional view of a first type of substrate usefulfor the packaging containers described herein;

FIG. 15B is a cross-sectional view of a second type of substrate usefulfor the packaging containers described herein; and

FIG. 15C is a cross-sectional view of a third type of substrate usefulfor the packaging containers described herein.

DETAILED DESCRIPTION

Filled tetrahedron-shaped containers may be formed from a web of sheetmaterial, such as paper stock, foil, or film, each of which has ameltable coating on at least one side. Such tetrahedral containers 2 areshown in FIG. 1A and FIG. 1B, which show the relative position of alongitudinal seal 4, a first transverse seal 6, and a second transverseseal 8. The first transverse seal 6 and the second transverse seal 8 arepositioned perpendicularly to one another. Typically, in production,longitudinal seal 4 is positioned on the back of tetrahedral container2. As shown, longitudinal seal 4 has a fin seal configuration (that is,the interior sides of the stock material abut, and are sealed to, oneanother). Alternately, longitudinal seal 4 may be an overlap seal, inwhich the stock material is lapped over itself (that is, an interiorside of the stock material is secured to an exterior side of the stockmaterial). The longitudinal seal 4 is off-set from the outermost edge ofthe transverse seal 6, as shown in FIG. 1B, to ensure that both thelongitudinal and transverse seals are robust. This is accomplished byhaving the longitudinal sealing portion of the packaging machine beoff-set (preferably at a 45-degree angle, although other degrees ofoff-set may be used) to the transverse sealing portion of the packagingmachine.

Tetrahedron-shaped containers are preferred for many applications,because of their lower surface-area-to-volume ratio, and, therefore,they will be referred to most often in this disclosure. However, itshould be understood that cushion-shaped containers 2′ (as shown in FIG.1C) may also be formed according to the teachings herein by adjustingthe position of sealing clamp jaws and pressure jaws, as will be readilyapparent to those of skill in the art. Similarly to tetrahedral-shapedcontainers 2, such cushion-shaped containers 2′ have a longitudinal seam4′ on one side and transverse seams 6′ and 8′ at opposite ends.

As shown in FIG. 2, the stock material 12 is conveyed through alongitudinal sealing portion of the packaging machine 120 and thenthrough a transverse sealing portion of the packaging machine 120. Theprocess of forming tetrahedron-shaped filled containers 2 begins with aroll 14 of pre-printed flat package stock 12. The stock material 12 maybe any suitable material, such as paper, foil, or film, which includes ameltable coating on at least one side. Representative configurations ofmulti-layered stock materials are shown in FIGS. 15A-15C, which will bediscussed further herein.

The speed and tension of sheet material roll 14 is controlled by a brakemechanism 16. The stock material 12 is supported on a suitable supportmember (not shown) and is delivered upwardly over a plurality of guiderolls supported by frame members secured to the machine 120. The stockmaterial 12 is delivered downwardly from the upper portion of themachine 120 through a web guide 20, which ensures that the stockmaterial 12 is correctly positioned in a horizontal, or transverse,direction for entry into the machine. One representative web guideassembly 20 is sold by Fife Corporation of Oklahoma City, Okla.,although other manufacturers sell devices that function similarly.

In the longitudinal sealing portion of the packaging machine, the stockmaterial 12 is conveyed through a tube-forming subassembly 24, aseal-heating subassembly 26, and a seal-pressing subassembly 28, withthe conveyance of the stock material being accomplished by atube-conveying subassembly 30. The resulting tube of stock materialincludes a longitudinal seal, which is preferably of the “fin”-sealtype.

Once the tube of stock material is formed, the tube is conveyed into thetransverse sealing portion of the packaging machine 130, which isoperated by a motor 100. In the transverse sealing portion of themachine, transverse seals are made by the interaction of a heated jaw 36(carried on a pair of chains 34) with a corresponding pressure jaw 38(on a pair of chains 32). A second set of heated jaws and pressure jawsis oriented perpendicularly to the set shown to form transverse seals ina perpendicular direction to those formed by the first set of heated andpressure jaws. The package contents are conveyed into the packages in acontinuous-fill operation through fill pipe 22, which extends throughthe longitudinal sealing portion of the packaging machine to an areajust above where the first transverse seal is formed.

Motor 100 is connected, via a drive belt, to one of the chains 34conveying the heated jaws 36. The remaining chains (including chains 32and the perpendicularly oriented chains not shown) are connected to oneanother by a plurality of interacting gears (not shown).

The string of filled, connected packages is then either conveyed to acutting mechanism, which separates the individual packages by bisectingthe transverse seals, or gathered into a bin for transportation to anoff-line cutting mechanism. Preferably, for expediency, the cuttingmechanism is in-line with the filling-and-sealing operation.

The first station is a tube-forming subassembly 24 (shown in detail inFIGS. 4 and 5) that bends the material 12, such that the longitudinaledges are aligned with one another with the interior sides of the sheetmaterial abutting each other. This configuration forms a “fin” shapearound a fill pipe 22 (as shown in FIG. 5), which acts as a mandrelaround which the tube of stock material 12 is formed. (Alternately, aseparate forming mandrel may be positioned over the fill pipe 22, ifdesired.) The fill pipe 22 extends within the tube 50 of stock materialand that extends to a point above the region where the transverse sealsare formed. From the tube-forming subassembly 24, the stock material 12passes through a fin seal-heating subassembly 26 (shown in greaterdetail in FIGS. 6A-6C), where the thermoplastic coating on the stockmaterial is melted so that a bond is formed between the adjacent,abutting edges of the stock material that make the fin.

After being heated by the seal-heating subassembly 26, the longitudinaledges of the stock material are joined. The sealed stock material isthen conveyed through a seal-pressing subassembly 28 (shown in greaterdetail in FIGS. 7 and 8) that applies pressure to the fin seal 4 tofurther secure the seal, resulting in the formation of a closed cylinder50 (i.e., a tube). Because the tube 50 is formed around the fill pipe22, it should be evident that the longitudinal seal 4 is formed when thetube 50 is empty and the stock material is dry (that is, above the levelof the product).

The tube-conveying mechanism 30 (shown in cross-section in FIG. 9) pullsthe stock material through the longitudinal sealing portion 200 of thepackaging machine 120. As the tube 50 of sheet material is conveyed fromthe longitudinal sealing portion 200 of the packaging machine 120 to thetransverse sealing portion of the packaging machine, the tube 50 isbrought into contact with a fin-folding guide 60, which pushes thelongitudinal fin seal 4 against the tube 50. The fin-folding guide 60 ismade of an angularly disposed strip of steel, having a bend at thedistal end thereof for contacting the fin seal. The longitudinal sealingportion 200 of the packaging machine is operated by a servo motor 300,shown in FIG. 3. Each of these subassemblies will be discussed in moredetail as follows, with respect to their respective Figures.

The stock material tube 50 is conveyed into the transverse sealingportion of the packaging machine 120. The transverse sealing portion ofthe machine 120 is operated by a motor 100, which is directly connected,via a belt, to one of the chains 34, which, in turn, is connected to theother pairs of chains by a plurality of gears (not shown).

To form such transverse seals 6, 8, as shown in FIGS. 1A and 1B, opposedsets of heated jaws 36 and pressure jaws 38 are used. Each transverseseal is formed by a heated jaw 36 (shown in more detail in FIG. 12 and,in an alternate form, in FIG. 13) that acts in cooperation with anunheated pressure jaw (shown in more detail in FIG. 14). Forconvenience, the heated jaw will be identified throughout thisdescription as heated jaw 36; however, it is to be understood thatheated jaw 436 functions in a similar way and may be used instead ofheated jaw 36, as needs dictate. The heated jaws 36 melt the coating onthe interior of the stock material 12, while the pressure jaws 38simultaneously push the stock material 12 against itself to form eachtransverse seal.

To this end, two sets of opposed, endless chains carrying heated jaws 36and corresponding pressure jaws 38 at fixed locations along the chainsare continuously and uniformly rotated by gears (not shown) driven bymotor 100. One opposed set of endless chains is represented by referencenumbers 32, 34, while the second opposed set of chains is axiallydisplaced perpendicularly to the first set of chains (depicted as chains33, 35 in FIG. 11). The second set of chains is positionedperpendicularly to the plane of the machine shown in FIG. 2 and, assuch, is not visible in this view. There are four chains per set, twochains on which the heated jaws are carried and two chains on which theopposing pressure jaws are carried. For ease of illustration, not allchains are shown in this Figure.

Heated jaws 36, mounted on the first set of chains 32, push againstcorresponding pressure jaws 38 and, in the action of pushing against oneanother, the jaws 36, 38 push the food product (e.g., the liquidcontents) from the area where the transverse seal 8 is to be made. Thejaws 36, 38 form a transverse seal below of the level of product in tube50 and simultaneously advance tube 50, via a pulling action, downwardlythrough the machine 120 in a continuous motion. In the production oftetrahedral packages, heated jaws 36 on each set of chains are spacedtwo package lengths from one another. The heated jaws on the first setof chains 34 are located between, and perpendicularly displaced from,the heated jaws on the second set of chains 35, so that the formation ofa second seal is one package length away from the first seal.

Due to the relative staggered, or interleaved, positioning of the jawson the first and second sets of chains (as shown in FIG. 11), a firsttransverse seal will be made by jaws carried on the first set of chains,with a second transverse seal being made by jaws carried on the secondset of chains. It can be seen that the continuously moving heated jaws36 will form a first seal in a region already occupied by the product,while the product is being supplied from the fill pipe 22. The movementof the driven chains advances the tube 50 downwardly through themachine, where a perpendicularly-spaced pair of jaws forms a secondtransverse seal (also in a region occupied by the product). The resultis a continuous chain of packages that is conveyed to a cutting means(not shown), wherein each of the transverse seals is severed along itslength to form individual tetrahedron-shaped packages. The presentprocess creates a string of linked packages that are subsequently cutinto individual units through the middle of the transverse seal. Forthis reason, it is desirable to make the transverse seal as robust aspossible.

FIG. 4 shows a cross-section of the tube-forming subassembly 24, astaken along line 4-4 of FIG. 3. The tube-forming subassembly 24 may beseen in larger scale in FIG. 9B. The tube-forming subassembly 24includes a forming ring with an aperture in the center thereof, in whichthe fill pipe 22 is centered. The tube-forming subassembly 24 alsoincludes a first forming ring panel 150, a second forming ring panel152, and a pair of adjustable fin spacing guides 154. The second formingring panel 152 includes a machined slot in which the longitudinal edgesof the sheet material 12 are positioned to facilitate production of thelongitudinal fin seal. The forming ring panels 150, 152 are boltedtogether (bolts not shown), so that one panel may be easily removed toallow for the removal and cleaning of the fill pipe 22. The tube-formingsubassembly 24 may have apertures of different sizes to accommodate fillpipes of different sizes (and, consequently, to produce packages ofdifferent sizes). The forming ring panels 150, 152 are preferably madeof stainless steel, but may be made of other durable, thermally stablematerial instead.

FIG. 4 also shows motor 300, which drives a plurality of threadedpulleys 304, 306, 308, which are connected to an idler roll 310. Thepulleys are connected by a belt 302. A pivoting pneumatic cylinder 190permits adjustment of the tension on the belt 302 by permitting themovement of the idler roll 310. Pulley 304 is connected to motor 300,via a drive shaft. Pulley 306 is connected, via a shaft, to a firsttube-conveying assembly 30, and, likewise, pulley 308 is connected, viaanother shaft, to a second tube-conveying assembly 30. Idler roll 310acts as a belt tensioner and is connected to the frame of the packagingmachine.

In the center of FIG. 4 is shown the longitudinal seal-heatingsubassembly, which has a pair of heater arms 160. Heater arms 160 areopened and closed via pneumatic cylinders 162. Such operation will bedescribed in greater detail, in reference to FIGS. 6A-6C.

FIG. 5 illustrates tube-forming subassembly 24 and the positioning ofthe sheet material 12 within the machined slot formed in forming ringpanel 152. The space between the fill pipe 22 and the aperture informing ring panels 150, 152 is very small, so that the sheet material12 is held securely in position for production of the longitudinal seal.Slots of different dimensions may be used to create fin seals ofdifferent size.

FIGS. 6A, 6B, and 6C show the operation of the longitudinal seal-heatingsubassembly 26. The longitudinal seal-heating subassembly 26 includes apair of heater arms 160 that are opened (as in FIG. 6A) and closed (asin FIGS. 6B and 6C) by pneumatic cylinders 162. The heater arms 160 arepivotally connected to one another. Each heater arm 160 includes aheater element 164 that provides heat to a heater arm face 166. In FIGS.6A, 6B, and 6C, the forming ring panels 150, 152 have been omitted toshow only the feed pipe 22 and the stock material 12. FIG. 6Aillustrates the open position of the heater arms 160. In FIGS. 6B and6C, the faces 166 of the heater arms 164 are in contact with the stockmaterial 12, causing the interior coating of the stock material to melt,or soften, in order to form the longitudinal seal.

Since the filling of the packages is a continuous process, the formationof the longitudinal seal is also a continuous process. The forming ofthe longitudinal seal 4 occurs while the stock material 12 is dry (thatis, before introduction of the package contents), whereas the formationof the transverse seals 6, 8, as will be discussed herein, occurs whenthe stock material 12 is wet (that is, the tube 50 of stock material isfilled with the package contents).

FIGS. 7 and 8 are cross-sectional views of the seal-pressing subassembly28. The seal-pressing subassembly 28 includes a pair of pressure rollers128, 128′ and a pneumatic pressure roller cylinder 130, which movespressure roller 128 from an open position to a closed position.Alternately, the pressure rollers 128, 128′ may be spring-activated. Theclosed position is illustrated in further detail in FIG. 8, which showsthe pressure rollers 128, 128′ converging on the sheet material andforming the longitudinal seal that produces tube 50. Although one set ofpressure rollers 128, 128′ is shown, two sets may instead be used. Thepressure rollers 128, 128′ may be made entirely of steel or may have asteel shaft with a urethane-coated flange.

FIG. 9A is a cross-sectional view of a portion of the tube-conveyingsubassembly 30. The tube-conveying subassembly 30 includes a pair ofpulleys, which are indicated on either side of fill pipe 22 as pulleys172 (pulleys 176 are not shown in this view). A stationary flanged guide174 is positioned between the pulleys 172, 176. A rubber belt 170 iswrapped around the pulleys 172, 176 and the guides 174 on each side ofthe packaging tube 50. The pulleys 172, 176 are positioned by the actionof pneumatic cylinders 180, in which the engaged position of the pulleys172, 176 is at the end of the stroke of the pneumatic cylinders 180.

The mechanics of the tube-conveying subassembly 30 are better shown inFIG. 9B. A motor 300 is connected to a belt 302, which is threadedaround pulleys 306, 308 and an idler roll 310. The idler roll 310 may bepositioned by an air cylinder 190. Pulley 306 is attached, via a firstshaft, to a first pulley 176, and a pulley 308 is attached, via a secondshaft, to a second pulley 176. As the pulleys 306, 308 are rotated, theshafts turn pulleys 176 in the directions shown by arrows in FIG. 9B. Asa result, the belts 170 around the pulleys 172, 176 are also set intomotion. Because there is a greater friction between the rubber belts 170and the packaging tube 50 than there is between the packaging tube 50and the fill pipe 22 (not shown), the contact between the pulleys 172,176 and the packaging tube 50 allows the packaging tube 50 to be pulledthrough the packaging machine.

FIG. 10A is a schematic representation of the transverse sealingsubassembly 220 of the present packaging machine. As shown in FIG. 10A,the pressure jaws 38 are located along a pair of chains 32, and theheated jaws 36 are located along a pair of chains 34. The tube 50 ofstock material is pulled downwardly through the traverse sealingsubassembly 220. A first pressure jaw 38 and a first heated jaw 36 comeinto contact with one another, as shown, during the rotation of theirrespective chains along an oval path. The chains 32, 34 carrying thepressure jaws 38 and the heated jaws 36, respectively, rotate inopposite directions, due to their placement within the transversesealing subassembly 220.

The motion of the chains 32, 34 causes a rolling contact between theheated jaw 36 and the pressure jaw 38. Initially, the lower edges of thefaces of the pressure jaw 38 and the heated jaw 36 come into contactwith each other, and the subsequent increasing contact between the jaws36, 38 forces the product (for example, the liquid contents) out of thetransverse seal area (that is, the area between the jaws 36, 38). Theremoval of the product from the seal area enables a consistenttransverse seal to be made across the width of the package, as theheated jaw 36 heats the tube 50 in the area of the seal, causing themeltable coating on the interior of the stock material to become molten.Simultaneously, the pressure jaw 38 pushes the molten seal areastogether, so that a strong, uniform seal 6 is made. The temperature ofthe heated jaw 36 at its face is typically between about 250° F. and450° F., depending upon the stock material 12 being used. The forceapplied by the pressure jaw 38 over the contact area is typically fromabout 200 pounds to about 800 pounds. Generally, the dwell time of thepackaging material in the area of transverse seal formation isapproximately from about 0.1 seconds to about 1 second, depending on thespeed of the packaging machine.

As discussed previously, in the formation of tetrahedral packages, anadditional set of heated jaws 36 and pressure jaws 38 are locatedperpendicularly to those shown in the illustration, each respectivelylocated along its own pair of roller chains (as will be described withreference to FIG. 11). These perpendicularly oriented sets of heatedjaws and pressure jaws form the transverse seals 8, in the same manneras described above for transverse seals 6.

Although the conveying mechanisms for the jaws 36, 38 are shown asroller chains, other mechanisms may be used, including, for example,solid belts, belts perforated with openings for receiving the jaws, flatchains, linked chains, O-ring chains, and the like. If belts are used,it may be desirable to make the belts from stainless steel to preventstretching with use, which could cause misalignment of the jaws.

FIG. 10A also illustrates a closed-loop, modified electrical system 140,which powers the heated jaws 36. Each heated jaw 36 includes anelectrical contact-containing back 510 having at least a pair ofelectrical contacts, which creates an electrical connection between aheater cartridge inside the heated jaw 36 and the power rails 140. Apair of power rails 140 is provided, at least one of which is configuredwith a base level portion 142 and a power-correction portion 144. Thebase level portion 142 of the power rails 140, which comprises themajority of the length of the power rails, maintains at least a minimumenergy level necessary to power the heater cartridges within the heatedjaws 36. The power-correction portion 144 of the power rails 140comprises a length on the power rails that is approximately equal to onepitch (that is, the distance between two adjacent heated jaws 36). Thepower-correction portion 144 supplies additional energy to any heatedjaw 36 that has a temperature measurement that is lower than the targettemperature for the heated jaws 36. The power-correction portion 144 ofthe power rails 140 needs only to be long enough to be in contact withone jaw 36 at a time.

The power rails 140 are controlled by a programmable logic controller(or “PLC”) 260 that includes a data transmission reader (not shown).When the heated jaw 36 passes a stationary antenna 270, the wirelesstransmitter 280 is activated, at which time the thermocouple on theheated jaws 36 takes multiple temperature measurements across the jawface. These measurements are then transmitted via a wireless transmitter280 (shown in more detail in FIGS. 12 and 13) back to the stationaryantenna 270. The stationary antenna 270 is mounted in close proximity(for example, between 0.375 inches and 0.5 inches) to the path of theheated jaws 36. From the antenna 270, the data is transmitted to the PLC260, which determines whether an adjustment needs to be made.

In practice, the PLC 260 compiles data for all of the heated jaws 36 ona particular pair of chains and makes adjustments to either the baselevel portion 142 of the power rails 140 or the power-correction portion144 of the power rails 140. If a particular heated jaw 36 exhibitstemperature readings that are lower than the other heated jaws 36, thePLC 260 increases the power in the power-correction portion 144 of thepower rails 140, when that particular heated jaw 36 contacts thepower-correction portion 144. If all of the heated jaws 36 exhibitlower-than-desired temperatures, then the PLC 260 will increase thepower in the base level portion 142 of the power rails 140. Adjustmentsto the base level portion 142 of the power rails 140 are made by settingthe heated jaw 36 with the highest temperature at the desiredtemperature for all of the heated jaws 36.

Conversely, if all of the heated jaws 36 exhibit higher-than-desiredtemperatures, then the PLC 260 may decrease the power in the base levelportion 142 of the power rails 140. In this way, the transverse sealingsubassembly 220 provides independent control for consistent temperaturesacross the face of the heated jaws 36 and from jaw-to-jaw, therebyensuring that consistent seals are formed in the transverse directionfrom package to package. Ideally, the temperature variation across theface of the heated jaws 36 and among the heated jaws 36 is no more thanabout 10° F. (or about 5° C.). The heated jaws on the other pair ofchains are similarly controlled by the PLC 260.

FIGS. 10B and 10C illustrate the back 510 of the heated jaws and theelectrical system 140 of FIG. 10A. As shown in FIG. 10B, the back 510 ofthe heated jaws includes a pair of electrical contacts 141′ and 142′.FIG. 10C is an isometric representation of the electrical system 140,showing the positioning of seven heated jaws around the power rails 141,142. Although seven heated jaws are shown, any number of jaws may beused. Power rail 141 may be an electrified rail or may be a neutralrail; for the sake of discussion herein, this rail will be referred toas a “common” rail. Power rail 142 is an electrified rail, which has apower-correction portion 144. As discussed above, the power-correctionportion 144 has a length that is approximately equal to one pitch (thatis, the length between two adjacent heated jaws). Electrical contact141′ is in contact with power rail 141, and electrical contact 142′ isin contact with power rail 142.

FIGS. 10D, 10E, and 10F illustrate an alternate embodiment to the heatedjaws and electrical system shown in FIGS. 10B and 10C. In thisembodiment, an even number of heated jaws are used, half of the heatedjaws having a back 612 with two electrical contacts 341′, 342′ and theother half of the heated jaws having a back 614 with two electricalcontacts 341′, 346′. As illustrated, the heated jaws each have anelectrical contact 341′, which is commonly positioned and which contactscommon rail 341.

FIG. 10F is an isometric representation of an electrical system 340,showing the positioning of eight heated jaws around three power rails341, 342, and 346. The heated jaws are arranged in an alternatingconfiguration, such that a heated jaw with back 612 is positionedbetween heated jaws with back 614 (and vice versa). Power rail 342includes a power-correction portion 344, and power rail 346 includes apower-correction portion 348. Because each heated jaw is powered by adifferent pair of power rails than its adjacent jaws—for example, afirst jaw is powered by rails 341, 342, and its adjacent jaws arepowered by rails 341, 346—the power-correction portions 344, 348 may beextended, in length, to approximately twice the pitch between adjacentjaws. Thus, two adjacent jaws may be corrected simultaneously, and thelength of time available to correct the power for the heated jaws istwice as long as the arrangement shown in FIGS. 10A and 10C.

FIGS. 10G, 10H, 10I, and 10J illustrate yet another embodiment of heatedjaws and a corresponding electrical system 540, in which the number ofheated jaws is divisible by three. FIGS. 10G, 10H, and 10I represent thebacks 710, 712, and 714 of three heated jaws, which are arrangedsequentially around power rails 541, 548, 546, and 542 (shown in FIG.10J). Each of the heated jaws has a common electrical contact 541′,which contacts common rail 541. The back 710 of the heated jaw of FIG.10G includes electrical contacts 541′ and 542′ and represents jaws thatare powered by contact with power rails 541, 542. The back 712 of theheated jaw of FIG. 10H includes electrical contacts 541′ and 546′ andrepresents jaws that are powered by contact with power rails 541, 546.The back 714 of the heated jaw of FIG. 10I includes electrical contacts541′ and 548′ and represents jaws that are powered by contact with powerrails 541 and 548.

As shown in FIG. 10J, power rails 542, 546, and 548 includepower-correction portions 543, 547, and 549, respectively. Thepower-correction portions 543, 547, and 549 may be extended, in length,to approximately three times the pitch between adjacent jaws. Thus,three jaws may be corrected simultaneously, and the length of timeavailable to correct the power for the heated jaws is three times aslong as the arrangement shown in FIGS. 10A and 10C.

Although the electrical systems described above represent variousembodiments that may be successfully employed, it should be understoodthat numerous variations may instead be used, including a system havingan n+1 number of rails, where n is the number of heated jaws. In such asystem, each heated jaw is powered by its own dedicated power rail, andall of the heated jaws share a common rail. Using this approach, thepower rails may be constantly adjusted during real-time, as measurementsindicate are necessary.

Further, although the electrical contacts have been illustrated as beingspring-loaded, other types of electrical contacts may be used,including, without limitation, contacts that straddle the power railsand contacts that slide along the power rails in contact with one orboth edges of the rails.

FIG. 11 illustrates the arrangement of multiple heated jaws 36 andpressure jaws 38 and the positioning of the stock material tube 50, asit is conveyed through the transverse sealing subassembly. For ease ofillustration, each pair of chains 32, 34, 35 is represented as a singlechain. Each of the pair of chains 33 is shown. A first set of heatedjaws 36 is located along a pair of chains 34, while the cooperative setof pressure jaws 38 is located along a pair of chains 32. A second setof heated jaws is conveyed along chains 35, while its cooperative set ofpressure jaws 38 is conveyed along chains 33. To create theperpendicular transverse seals 6, 8 that are characteristic of atetrahedral container 2, the respective sets are perpendicular to oneanother and are spaced one package length apart from one another. Alongeach chain 32, 33, 34, 35, the jaws 36 or 38 are positioned two packagelengths apart from each other, so that the transverse seals 6, 8 areappropriately spaced.

The longitudinal fin seal 4 is visible as the stock material tube 50enters the transverse sealing area. As indicated by phantom lines, finfolding guide 60 contacts the longitudinal fin seal 4 and pushes itagainst the tube 50. In those instances where a meltable coating ispresent on the outside of the stock material, the formation of thetransverse seals 6, 8 tends to melt the fin seal 4 (in the area of thetransverse seal) into position against the package. In instances where amanufacturer chooses to produce a pillow-shaped package 2′, only one setof opposed heated jaws 36 and pressure jaws 38 is necessary. In bothinstances, depending on the desired package size, the size, number, andposition of the heated jaws 36 and pressure jaws 38 may be adjusted.

FIGS. 12 and 13 illustrate two different versions of a heated jaw(identified as 36 and 436).

As shown in FIG. 12, the heated jaw 36 includes a heated jaw base 290,which connects to chains 34 or 35. The heated jaw 36 includes a heatedjaw block (made of face component 296 and rear component 298) thathouses a heater cartridge 284 with uniform power density. The rearcomponent 298 of the heated jaw block is attached to an insulator block294, which couples with a transmitter housing 282 at one end of theinsulator block 294. The wireless, digital transmitter 280 is positionedwithin the transmitter housing 282, which (along with the insulatorblock 294) is attached to base 290. The electrical contacts are attachedto the back 510 of the base 290 via intermediate insulating washers.

A thermocouple 281 for measuring the temperature of the jaw face ispositioned inside an axially bored channel that terminates in theapproximate center of the heated jaw block 296 as close to the jaw faceas possible. Readings from the thermocouple are transferred to thewireless digital transmitter 280, which is held in a transmitter housing282. As described previously with reference to FIG. 10, the wirelesstransmitter 280 digitally transmits the data to a stationary antenna260, which relays the information to a reader and programmable logiccontroller 270. These wireless transmitters 280, which are manufacturedby MicroStrain, Inc. of Williston, Vt., are accurate, precise, andreliable and show little variation or drift over long periods of use.

The wiring for the heater cartridge 284 is threaded through theinsulator block 294 and is terminated within the spacer 292. Within thebase 290 is an electrical connection housing, which includes a pair ofelectrical contacts 510 that contact the power rails describedpreviously.

FIG. 13 illustrates a second version of the heated jaw 36. In theseFigures, the heated jaw is identified as heated jaw 436. Connected tothe base 490 is a spacer 492 (which may optionally be formed into thebase 490). An insulator block 494 is connected to, and is positionedbetween, the spacer 492 and a heated jaw block 496. The heated jaw block496 includes a jaw face, a thermally conductive core 495, and a heatercartridge 484. The heater cartridge 484 is surrounded by a thermallyconductive core 495 and is held in position by a cartridge holder 485.The heater cartridge 484 has a variable power density, resulting fromthe localized placement of the heater coils at each end of thecartridge. Such a configuration is useful to combat heat loss at therespective ends of the heated jaw block 496 and to ensure uniform heattransfer across the jaw face (as the heat is distributed evenly by thethermally conductive core 495).

The thermally conductive core 495 is made of a material that is highlythermally conductive (that is, which exhibits a high k value indicativeof ability to conduct heat). For this purpose, the core is preferablymade of copper, aluminum, gold, silver, antimony, zirconium, tungsten,alloys of such metals, and the like. Aluminum and copper are the mostcost-effective materials. Preferably, the thermally conductive core 495is copper or a copper-containing alloy, because of its high thermalconductivity. The thermally conductive core 495 promotes uniform heatingacross the face of the heated jaw 436 and also facilitates themaintenance of the face of the heated jaw 436 at the desiredtemperature.

Heated jaw 436 operates on the same basic principles as heated jaw 36.In FIG. 16, the wiring from the transmitter 480, which is connected to athermocouple, is positioned inside a bored channel in the heated jawface 496. The temperature readings from the thermocouple 481 aretransmitted digitally from the transmitter 480 to the antenna 270 (shownin FIG. 10). The wiring of the heater cartridge 484 is threaded throughthe insulator block 494 and support component 492 before being attachedon the back of the base 490 to two or more electrical contacts thatcontact the power rails described previously.

In the case of both heated jaw 36 and heated jaw 436, the heated jawface is preferably made of a hard, thermally stable material, such asheat-treated stainless steel having a hardness value on the Rockwell-Chardness scale of about HRC 58. It was found that other materials, suchas heat-treated brass, for example, having a hardness value of HRC 27,lacked the hardness to resist damage from repeated contact with thepressure jaws. In those instances where the stock material includes ameltable coating on the outside, it may be desirable to use a heated jawface with a non-stick coating to facilitate release of the transverseseals from the heated jaws.

The patterned jaw face, as illustrated, using multiple intersectinglines, promotes seal integrity by providing a plurality of channelsinside the tube of packaging material through which the liquid contentsmay be pushed upward as the transverse seal is made. It should be notedthat the patterns in the jaw face are formed in the transverse seals onthe package and, thus, may be desirably modified for aesthetic purposesas well as functionality, taking the properties of the stock materialinto consideration.

The concept of package “headspace” is familiar to those skilled in theart of intermittent-fill packaging. In packages such as milk cartons,headspace is the area filled with air between the level of the productand the top of the container. In continuous fill packaging, such as ispresently described, the filled packages have no headspace, becausethere is no air in the filled packages. However, to mimic the effect ofhaving a headspace, it may be desirable under some circumstances tocreate a “false headspace” by slightly compressing the package as it isbeing sealed.

This false headspace may be achieved by the addition of curved plates422, 488 to the top and bottom of the heated jaw 436. The upperheadspace plate 422 is attached to mounting plate 420, while the lowerheadspace plate 488 is attached to a mounting plate 498 on the bottom ofthe heated jaw 436. The mounting plates 420, 498 are attached to theinsulator block 494, which prevents the headspace plates 422, 488 frombecoming heated by contact with the heater jaw block 496. If theheadspace plates 422, 488 become heated, as in previous false-headspacemechanism designs, their contact with the stock material may damage theappearance of the stock material (for instance, if the outside of thepackaging material is printed, it may be smeared by heat from theheadspace plates).

The headspace plates 422, 488 engage the tube of packaging material andslightly compress the tube, just before formation of the transverseseals. This compression results in the sealed package being undertension, such that, when the package is opened, a slight vacuum isformed. As a result, the package contents are “pushed” into the bottomof the package by air rushing into the package, thus preventing thecontents from splashing out onto the consumer.

FIG. 14 illustrates a pressure jaw 38, which acts in cooperativerelation with either the heated jaw 36 or the heated jaw 436. Thepressure jaw 38 is a much simpler element, including a base 390 and apressure jaw face 396. The pressure jaw face 396 may be made ofdifferent materials, depending upon the stock material being used forthe packages. For example, if the stock material is a coated paper, thepressure jaw face 396 may be stainless steel. If the stock material is amulti-layer film, then the pressure jaw face 396 may be made of rubberor a rubber-like material. In either instance, the pressure jaw face 396is preferably made from a heat resistant, resilient, and durablematerial. When the pressure jaw face 396 is rubber or rubber-like, itmay be made in a domed shape, such that the compression of the pressurejaw 38 against the heated jaw 36 helps to force the product contents outof the seal area.

FIGS. 15A, 15B, and 15C are representative of various stock materialsuseful for making packages in accordance with the teachings herein. Ineach Figure, the top layer represents the outermost layer of thepackaging container. FIG. 15A illustrates a multi-layer film structure600, in which the outermost layer is a polymer film layer 602. Thepolymer film layer 602 may be printed on either side, although, for manyapplications, reverse printing on the lower side of the polymer filmlayer 602 may be preferable. The central layer in the multi-layer filmstructure 600 is a polymer film 606 that is surrounded on each side by arelatively thin film layer 604. The relatively thin film layer 604 actsas a binder for the other layers. The polymer film 606 may be metallizedor otherwise treated for barrier properties, as desired. A meltablesealant film layer 608 forms the innermost layer of the structure 600.

Polyester films are well-suited for layers 602, 606, though otherpolymers (such as polypropylene or nylon) may be used instead. Theselayers 602, 606 preferably have a thickness in the range of about 48gauge, but other thicknesses may be used.

FIG. 15B illustrates a multi-layer foil structure 650, in which theoutermost layer is a polymer film layer 652. As before, the polymer filmlayer 652 may be printed only either side. The central layer in themulti-layer foil structure 650 is a foil 656 that is surrounded on eachside by relatively thin film layers 654, 658. It may be desirable tomake the film layer 654 an opaque layer (such as a white layer), so thatthe foil layer 656 is not apparent from the outside of the package. Ameltable sealant film layer 660 forms the innermost layer of thestructure 650.

FIG. 15C illustrates a multi-layer coated paper structure 680, in whichthe outermost layer is a coated paper layer 682. A tie layer 688connects the coated paper layer 682 to a barrier film 684 that ispositioned on the back side of the coated paper layer 682. As with theother multi-layer stock materials, a meltable sealant film 686 forms theinnermost layer of the structure 680. The paper layer 682 preferablycontains an outer coating, which protects the outside of the packagingcontainer.

When making packages having a longitudinal fin seal, such as thosedescribed herein, it is unnecessary to have a meltable coating or layeron the outermost side of the packaging material. This advantage is dueto the inside-to-inside sealing of the packaging material, whichrequires only that the innermost layer of the stock material bemeltable. Thus, any printing applied to the face of the outermost layeris maintained throughout the sealing and filling process without beingsmeared.

Although reference has been made throughout this description to thepackage contents as being consumable foodstuffs, it should be readilyapparent to those of skill in the art that the packages and equipmentdescribed herein are equally useful in packaging inedible products, suchas adhesives, caulks, detergents, and the like.

1. A liquid-filled tetrahedral package, said package being comprised ofa strip-shaped sheet of packaging material having opposed longitudinaledges, an exterior surface, and an interior surface, the interiorsurface having a meltable coating, said package having a longitudinalfin seal and having a first transverse seal on one end of said packageand a second transverse seal on an opposite end of said package, saidsecond transverse seal being substantially perpendicular to said firsttransverse seal.
 2. The package of claim 1, wherein said longitudinalfin seal comprises the longitudinal edges of said sheet of packagingmaterial, said longitudinal edges having been aligned such that, in thearea of said longitudinal fin seal, the interior surfaces of saidpackaging material contact one another and having been heated andpressed to form said longitudinal fin seal.
 3. The package of claim 2,wherein said longitudinal fin seal lies substantially flat against saidpackage.
 4. The package of claim 1, wherein the packaging material isprinted.
 5. The package of claim 1, wherein said packaging material hasa construction selected from the group consisting of a multi-layer paperconstruction, a multi-layer foil construction, and a multi-layer filmconstruction.
 6. The package of claim 1, wherein the packaging materialis a multi-layer film structure comprised of an outermost layer ofpolymer film, a central layer of polymer film wherein the central layeris surrounded on each side by a thin film layer, and a meltable sealantfilm layer that forms the innermost layer of the package.
 7. The packageof claim 6, wherein the central layer of polymer film is comprised ofmaterial selected from the group consisting of polyester, polypropyleneand nylon.
 8. The package of claim 6, wherein the central layer ofpolymer film is metallized.
 9. The package of claim 6, wherein theoutermost layer of polymer film is comprised of material selected fromthe group consisting of polyester, polypropylene and nylon.
 10. Thepackage of claim 6, wherein the packaging material is printed on theoutermost layer of polymer film.
 11. The package of claim 1, wherein thepackaging material is a multi-layer foil structure comprised of anoutermost layer of polymer film, a central layer of foil wherein thecentral layer is surrounded on each side by a thin film layer, and ameltable sealant film layer that forms the innermost layer of thepackage.
 12. The package of claim 11, wherein the thin film layer isopaque.
 13. The package of claim 1, wherein the packaging material is amulti-layer coated paper structure comprised of an outermost layer ofcoated paper, a tie layer connecting the coated paper layer to a barrierfilm, wherein the barrier film is positioned on the back side of thecoated paper layer, and a meltable sealant film layer that forms theinnermost layer of the package.
 14. The package of claim 13, wherein theoutermost layer of coated paper further comprises a protective outercoating.